Circuit interrupter



March 4, 1941. F. GUNTHER 2,233,605

CIRCUIT INTERRUPTER Filed Nov. 22, 1938 INVEN'TOR fran z Gun/her:

@ (/v/ n t BY q f ATToRNE Patented Mar. 4-, 1941 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER ration of Pennsylvania Application November 22, 1938, Serial N 0. 241,769 In Germany December 23, 1937 15 Claims.

The invention relates to electrical switches or circuit interrupters in general, and more particularly to circuit interrupters of the type having a movable contact member whichis operated at relatively high speed, and which is moved through a substantial distance in order to provide asafe gap in the open position.

In interrupters of the type mentioned above, it has been found desirable to use roller type contacts for conducting current to the movable contactor switch member inorder to reduce resistance to movement of the contact, and to more readily break any welding, corrosion, or ice formation on the movable contact. It has been considered necessary, however, in the case of high speed interrupters equipped with such roller contacts, to provide special braking or dashpot devices for braking or absorbing the large kinetic energy of the movingparts near the endsof the stroke of the latter.

An object of the present invention is the provision of a circuit interrupter of the class described equipped with roller contacts, in which the braking effect required near the ends of the stroke of the movable contact is produced by the roller contacts themselves.

Another object of the invention is the provision of a circuit interrupter embodying a device including roller contacts for conducting current to .the movable contact, in which the device and rollers offer only a very small resistance to initiation of the switching movement and to move- ,ment through the major portion of the stroke of the movable contact, and which automatically exert a relatively strong braking effect on the movable contact as it approaches either end of its stroke.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following description of one embodiment thereof when read in conjunction with the accompanying drawing, in which:

Figure 1 is a side elevational view of a circuit interrupter constructed in accordance with the invention;

Fig. 2 is an enlarged side elevational View of the contact and braking device;

Fi 3 is a Vertical sectional view of the device takensubstantially on the line III.-III of Fig. 2; and

Fig. 4 is a plan view of the device shown in Fig. 2.

Referring to Fig. 1 of the drawing, which shows a complete circuit interrupter embodying the features of the invention, the reference nu- 5 mera-l 5 designates a base or frame on which is mounted a pair of spaced insulators I and 9. The lower insulator 1 supports an arc extinguishing device in the form of an explosion pot ii containing oil or other suitable arc extinguishing substance. A stationary contact means (not shown) is mounted within the pot II and is electrically connected to a terminal I3. The upper end of the pot H is provided with an opening for receiving a vertically movable contact member or switch blade 5.

The contact member 15 is pivotally connected at its upper end to the free end of rocking lever H, the opposite end of which is secured to an operating shaft it which is rotatably mounted in the frame 5. The operating shaft 18 may be connected to any suitable type of operating mechanism which is operable to cause relatively high speed movement of the movable contact member Hi to open and to closed circuit positions.

' The upper insulator 9 has secured thereto a device 19 which serves to conduct current to the movable contact member l5, and which is also automatically operable to exert a braking effect on the movable contact member l5 only as it approaches either end of its switching movement to absorb the kinetic energy of the moving parts. The device is, which is shown in detail in Figs.

2, 3 and 4, comprises a support it of conducting material on which is mounted a plurality of contact rollers 23 and a plurality of cooperating braking members 25 also of conducting material.

The support 2!, which is preferably die cast, has a perpendicular mounting base 21 formed at one end by means of which it is secured to the insulator 9. The opposite end of the support 2| is formed to provide a terminal 29 for connecting the circuit interrupter to an electrical circuit. The body portion of the support 2| is provided with a centrally disposed vertical opening 3! through which the movable contact member l5 passes, and with suitable openings and recesses on its opposite sides for accommodating the contact rollers 23 and the brake members 25.

The contact rollers 23 are disposed to engage the opposite sides of the movable contact member l5, and are carried by a pair of roller carriers 33 (Fig. 3) which are loosely mounted on opposite sides of the support 2|. Each roller carrier 33 comprises a pair of spaced parallel arms 35 (Figs. 2 and 4) which are disposed in vertical recesses 31 (Fig. 4) provided therefor on the opposite sides of the support 2|. The upper -'ends of the roller carrier arms 35 are rounded and engage the upper side portions 39 (Fig. 3) of the support 2|. The lower portions of the roller carrier arms 35 are provided with aligned vertical guide slots 4|, and the contact rollers 23 are mounted on transverse pins 43 which are movable in the guide slots 4|. riers 33 are held in place and prevented from falling out of the open sides of the support 2| by means of the brake members 25.

The two brake members 25, which are disposed on opposite sides of the support 2|, are carried for pivotal movement intermediate their ends on a pair of transverse pins 45 which engage in recesses 41 provided therefor in a pair of spaced projections 48 formed on the opposite sides of the support 2|. The upper arms of the brake members extend inwardly terminating in rounded ends 49 which are engaged in semi-circular recesses formed in the outer edges of the roller carriers 33 (Fig. 3). The roller carriers 33 are thus held in mounted position on the support 2|. A pair of tensioned springs 5| connect the extended ends of the transverse pins 45, and these springs serve to bias the brake members 25 inwardly towards each other and also function to hold all of the contact parts assembled in mounted position on the support 2|.

'The movable contact member |5, which in the embodiment shown has a rectangular crosssection, is provided with a portion 53 of reduced cross-section or thickness for a portion of its length for cooperating with the contact rollers 23 and device IS. The ends of the reduced portion 53 increase in thickness to join the non-reduced portion of the contact member |5. A relatively small clearance is provided between each contact roller 23 and the lower end of its corresponding brake member 25 to permit the rollers 23 to turn freely during the time they engage the reduced portion 53 of the contact member |5. For this purpose the lower ends of the brake members are provided with lateral extensions 51 (Fig. 2) which engage the lower cutaway edges of the outwardly extending projections 48 of the support 2| during the time the contact roller 23 engages the reduced portion 53 of the contact member 5. v

The electrical circuit through the interrupter extends from the upper terminal 29, through the support 2|, the roller carriers 33 and the brake members 25 to the contact rollers 23, to the movable contact member l5, and through the movable contact member to the stationary contact means and lower terminal |3 when the interrupter is closed. The springs 5| provide ample contact pressure between the contact parts when the interrupter is in closed position. It will be noted that the contact areas of engagement between the various contact parts of the device l9 closed circuit position, the contact roller pins 43 are at the lower ends of the slots 4| in the roller carriers 33, and the contact rollers engage the upper non-reduced portion 55 of the contact member l5, so that the contact rollers 23 and the The roller car-f lower ends of the brake members 25 are spread apart and the springs 5| expanded. This position of the parts causes a relatively high pressure engagement of the lower ends of the brake members 25 on the contact rollers 23, the contact rollers 23 on the movable contact member l5, the upper ends of the brake members 25 against the roller carriers 33, and the upper ends of the roller carriers 33 against the support 2|. Thus all of the contact parts are in pressure engagement to provide a good current connection to the movable contact member |5.

When the movable contact member 15 is moved upwardly to open circuit position, the contact rollers 23 offer only a relatively small resistance to such movement due to rolling friction as the contact rollers 23 roll upwardly on the lower arms of the brake members 25, and also roll on the contact member |5. During this initial portion of the opening movement, the pins 43 move upwardly in the slots 4|. As soon as the contact member I5 is moved upwardly a relatively small distance, the rollers 23 roll on to the reduced portion 53 of the contact member l5, and during the continued upward movement of the movable contact member, the rollers 23 run on the reduced portion 53 of the contact member and turn freely since they are no longer in pressure engagement with the brake members 25. As the movable contact member approaches full open circuit position at the completion of the switching movement, the contact rollers 23 run on to the lower unreduced portion 55 of the contact member l5 which causes them to be forced outwardly against the brake members 25 thus causing the brake members 25 to be forced apart against the tension of the springs 5|. At approximately the same time, the roller pins 43 have reached the upper ends of the slots 4|, so that further upward movement of the roller 23 is prevented. As a result, the brake members 25 exert a strong braking effect on the final movement of the movable contact member |5 absorbing the kinetic energy of the moving parts.

When the movable contact member is moved from the open circuit position downwardly to closed circuit position, substantially the same action takes place. The contact rollers 23 offer only a relatively small resistance at the initiation of the closing movement due to the fact that the rollers roll downwardly along the lower arms of the brake members 25, so that they offer only rolling friction to the initial downward movement of the contact member. By the time that the contact member has moved downwardly a relatively small distance, the contact rollers 23 roll on to the reduced portion 53 of the contact member. During the continued downward movement, the contact rollers 23 engage the reduced portion 53 and turn freely, since they are no longer in pressure engagement with the brake members 25. As the contact member approaches closed circuit position at the completion of this bers 25 to engage the rollers-with a relatively high pressure, and thusexert a braking effect on the finalclosing movement of the contact member.

The rollers 23 engage the brake members 25 at points closer to the pivot axis 45 of the brake members during the final portion of the circuit opening movement than they do during the final portion of the closing movement, so that during the circuit opening movement the breaking force acts on a highly reduced moment arm of the brake members 25.

If desired, the parts may be so arranged that a larger braking efiect is produced at one end of the movement of the movable contact member than at the other end of its movement. This result can easily be accomplished, for example, by changing the shape or thickness of the movable contact member l5 at one end of the reduced portion thereof.

From the above description, it will be seen that the invention provides a simple and inexpensive device for conducting current to the movable contact member of a circuit interrupter or switch, and which is also automatically operable to exert a braking effect on the movable contact member as it'approaches either end of its movement, and yet which oifers only a relatively small resistance at the initiation of the switching movement of the contact member.

While the invention has'been disclosed in accordance' with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be made without departing fromthe spirit of the v invention.

I claim as my invention":

1. In a circuit interrupter, a switch member movable in one direction to closed position and in an opposite direction to-open position, contact means comprising a contact roller engageable with said switch member, and a brake member engageable with said roller, said switch member having a portion of reduced cross-section, said roller engaging the reduced portion of said switch member during a predetermined part of the movement of saidswitch' member to offer only a relatively smallre'sistan-ce to movement of said switch member, a'ndengaging the non-reduced portion of saidswitch member as said switch member approaches one end of its movement to cause said brake'm'emberto' effect pressure engagement with said roller and exert a braking effect on said'switchmember.

2. In a circuit interrupter, a switch member movable in one direction to closed position and in an opposite direction to openposition, means comprising at least one contact roller engageable with said switch member and a cooperating-brake member engageable with saidroller, said switch member having aportion of reduced cross-section of predetermined length, said roller engaging the reduced, portion of said switch member during a predetermined part of the switching movement of said switch member and offering only a relatively small resistance to movement of said switch.- member clue to rolling friction, and said roller running on tothe non-reduced portion of said switch member as said switch member approaches either end of its movement to cause said brake member toeffect pressure engagement with said. roller to exert a. braking effect on said switch member.

3.'In a circuit interrupter, a switch member movable in one direction to closed position and in an opposite direction to open position, means comprising a plurality of contact rollersenga ing said switch member, a plurality of brake members engageable with said rollers and biased toward said rollers, said switch member having a portion of its length of reduced cross-section, said rollers engaging said reduced portion during a predetermined portion of the switching movement of saidswitch member to'oiTer only'a relatively small resistance to such movement, and said rollers running on to the non-reduced portion of the switch member as it approaches either end of its movement to cause said rollers to engage said brake members and exert a braking effect on said switch member.

4. In a circuit interrupter, a switch member movable in opposite directions to open and closed position, means comprising a contact roller,.engaging said switch member, a carrier for said roller, a brake member pivotedintermediate its ends engageable with said roller'at one end and engaging said roller carrier at the other end, said switch member having a portion of reduced cross-section of predetermined length, said roller engaging said reduced portion of said switch member during a predetermined part of the switching movement of said switch member and ofiering only a relatively small resistance to movement of said switch member, said roller running on to the non-reduced portion of said switch member as said switch member approaches either end of its movement to cause said braking member to effect pressure engagement with said roller and exert'a braking effect on said switch member.

5. In a circuit interrupter, a switch member movable in opposite directions to open and to closed circuit position, means comprising a plurality of contact rollers engaging the opposite sides of said switch member for conducting current thereto, carriers for said rollers, a pair of brake members on opposite sides of said switch member mounted for pivotal movement intermediate their ends and for limited movement toward and away from each other, said brake members having their one arms engageable with said rollers and their opposite arms engaging said roller carriers, spring means biasing said brake members toward one another, said switch member having a reduced portion of predetermined length engaged by said rollers during a predetermined part of the switching movement of said switch member to cause said rollers to offer only a relatively small resistance to movement of said switch member, said rollers running on tothe unreduced portion of said'switch members when said switch member approaches either end of its movement for causing said rollers to efiect pressure engagement with saidbrake member and thereby exert a braking effeet on saidswitch member.

6. In a circuit interrupter, a switch member movable in opposite directions to open and to closed circuit position, means comprising a plurality of contact rollers engaging the opposite sides of said switch member for conducting current thereto, carriers for said rollers disposed on opposite sides of said switch member and movable toward and away from each other, a pair of brake members on opposite sides of said switch member mounted for pivotal movement intermediate their ends on a pair of supporting pins which are disposed on opposite sides of said switch member perpendicular to the path of movement of the switch member, the upperends 7 member at the initiation of switching movement,

and for causing said rollers to efiect pressure engagement with said brake members and switch member when said switch member approaches either end of its movement to exert a braking effect on said switch member.

. '7. In a circuit interrupter, a switch member movable in opposite directions to open and to closed circuit positions, means for conducting current to said switch member, and for automatically exerting a braking efiect on said switch member only when it approaches either end of its movement, said means comprising a plurality of contact rollers engaging opposite sides of said switch member, carriers for said rollers, a pair of brake members on opposite sides of said switch member supported for pivotal movement intermediate their ends by a pair of supporting pins disposed on opposite sides of said switch member perpendicular to the path of movement of said switch member, the one arms of said brake members engaging and supporting said roller carriers and the other arms of said brake members being engageable by said rollers, means mounting said supporting pins for bodily movement laterally toward and away from each other, and spring means connecting the ends of said pins for biasing said pins and brake members toward each other and for holding all of said parts together, said switch member having a portion of reduced cross-section of predetermined length cooperating with said' rollers.

8. In a circuit interrupter, a switch member movable in opposite directions to open and to closed circuit position, means for conducting current to said switch member, and for automatically exerting a braking efiect on said switch member only when it approaches either end of its movement, said means comprising a plurality of contact rollers engaging the opposite sides of said switch member, carriers for said rollers disposed on opposite sides of said switch member and provided with guide slots extending parallel to the path of movement of said switch member, said rollers being mounted on pins movable in said slots, and a pair of brake members disposed on opposite sides of said switch member biased toward each other and engageable by said rollers when said switch member is adjacent either end of its movement, said switch member having a portion of reduced thickness for a portion of its length for cooperating with said rollers.

9. In a circuit interrupter, a switch member movable in opposite directions to open and to closed circuit position, means for conducting current to said switch member, and for automatically exerting a braking efiect on said switch member only when it approaches either end of its movment, said means comprising a plurality of contact-rollers engaging the opposite sides of said switch member, carriers for said rollers disposed 'on opposite sides of said switch member and pro vided with guide slots extending parallel to the path of movement of said switch member, said rollers being mounted on pins movable in said slotsQa pair of brake members on opposite sides of said switch member mounted for pivotal movement intermediate their ends to provide arms of different length the one'arms of said brake members engaging said roller carriers and the other arms being engageable by said rollers when said switch member is adjacent either end of its movements, and spring means biasing said brake members towards each other, said switch member having a portion of its length of reducedthick ness for cooperating with said rollers, said rollers engaging said braking members at points closer to the pivot axis of said brake member when the switch member approaches open circuit position than when said switch member approaches closed circuit position. i

10. In a circuit interrupter, a contact member, one or more contact rollers engageable with said contact member, a brake member engageable with said one or more rollers, said contact memher and said one or more contact rollers being movable relative toeach other during switching movements of said interrupter, and means for causing said one or ,more contact rollers to offer only a relatively small. resistance to relative movement of said contact parts at the initiation of switching movement, and means for causing said brake member to effect pressure engagement on said one or more rollers during the latter part of the switching movement to exert a braking effect on said switch member.

11. In a circuit interrupter, relatively movable contact parts comprising a contact member,- a contact roller engageable with said contact member, a brake member engageable with said contact roller, means for causingsaid contact roller to become disengageable with said brake member and to offer only a relatively small resistance to the relative movement of said contact member at the initiation of switch movement, and for caus ing said brake member to engage said contact roller during the latter part of switch movement to effect thereby a relatively large resistance to motion of said contact member. I

12. In a circuit interrupter, a switch member movable in one direction to closed position and of said switch member at the initiation of switching movements thereof.

13. In a circuit interrupter, a contact member movable in one direction to closed-circuit posi-' tion and in an opposite direction to open-circuit position, means comprising one or more contact rollers engageable with said contact member for conducting current thereto, one or more brake members engageable with said one or more contact rollers as said contact member approaches either end position toexert thereby a braking eflect on the motion of said contact member, saidmeans being operable to cause disengagement'of said one or more .brake members with said one or more contact rollers to offer only relatively slight resistance to movement of said contact member at the initiation of switching movements thereof,

14. In a circuit interrupter, a switch member movable to open and to closed circuit position, one or more contact rollers engageable by said switch member, one or more brake members engageable with said one or more contact rollers, and means for causing reaction between said brake and roller members with a consequent braking effect on said switch member only during completion of the switch opening or closing movement, said means being operable to allow relatively free motion of said switch member during the initiation of switch opening or closing movement.

15. In a circuit interrupter, a switch member movable to open andto closed circuit position, actuating means for said switch member, one or more contact rollers engageable by said switch member, one or more brake members engageable with said one or more contact rollers, means for causing said one or more brake members to react on said one or more contact rollers to effect thereby a relatively high contact pressure between said one or more contact rollers and said switch member to brake the motion of said switch member during the completion of the opening or closing movement of said switch member, said means causing said one or more rollers to offer only a relatively small resistance to the initiation of such opening or closing movement of said switch member.

FRANZ GfiNTHER, 

